Electric control system



March 7, 1933. L. DEVOL 1,900,406

ELECTRIC CONTROL SYSTEM Filed April 16, 1951 4 Sheets-Sheet 1 )J'l no gmey Saruiw Lap INVENTOR.

L- De vo March 7, 1933. DEVOL 4 1,900,406

ELECTRIC CONTROL SYSTEI Filed April 16, 1931 4 Sheets-Sheet 2 INVENTOR.

L De 1/0 I,

M 1 A TTORNEY.

March 7, 1933. L. DEVOL 00 06 smacmuc comm. sysml Filed April 16. 1931 4' Sheets-Sheet a Fm0rg noy Lhp Service 295 INVENTUR.

L Dav/n1, I

ATTORNEY.

March 7, 1933. DEVOL 1,900,406

ELECTRIC CONTROL SYSTEM Filed April 16, 1931 4 Sheets-Sheet 4 INVENTOR.

L De v a I, BY

/+- ATTORNEY.

Patented Mar. 7, 1933 UNITED STATES.

PATENT? OFFICE;

LEE DEVOL, OF WILKINSBUB 'G, PENNSYLVANIA, ASSIGNOB TO THE UNION SWITCH &

SIGNAL COMPANY, 03' SW'ISSVALE,v PENNSYLVANIA, A CORPORATION 01 rm- SYLVANIA ELECTRIC com'nor. srs'rmr Application filed April '16,

My invention relates to electric control systems,and articularly to systems for the controlling 0 the brakes of a railway tram.

I will describe certain forms of systems embodying my invention, and will then pomt out the novel features thereof in claims.

In the accompanying drawings, Figs. 1 and 2 are diagrammatic views of one form of system embodying my invention, suitable for controlling the brakes of a railway train. The apparatus disclosed in Flg. 1 1s that located at the control point, whlch in this mstance, is on the locomotive, and the apparatus disclosed in the Fig. 2 is that located at another point on the train at whlch there IS an auxiliary apparatus adapted to reproduce the functions of the usual engineer s brake valve on the locomotive. Figs. 3 and 4 are diagrammatic views of a second form of system embodying my invention, also suitable for the control of train brakes, with Fig. 3 being the apparatus mounted at the control point, and Fig. 4 being the apparatus installed at some other point on the train. While the location of the apparatus shown in both Figs. 2 and 4 may be in each case at any point on the train, it will be spoken of in this description as being carried in the caboose of the train.

In my invention, impulses of modulated oscillations or impulses of non-modulated cur rent are exchanged between the two locations of the apparatus. Thus in the accompany-- ing disclosures impulses are exchanged between the locomotive and the caboose of a railway train. These impulses of current are of two or more types with each type of impulses accomplishing a specific function. One type of these impulses I shall speak of as selecting impulses and a second type as energizing or operating impulses. A third type of impulses, when used, will be referred to as signal impulses. The distinction between these different types of impulses may take different forms, such, for example, as different frequencies of alternating current, or a carrier current modulated at different frequencies, or

again the distinction between the different types of impulses may be that of the duration of the impulses, one type being short impulses and another type being long impulses. Again the different types may each consist of a ifierent distinctive group of im ulses.

In the form of the apparatus of igs. 1 and 2 the distinction between the difi'erent ty 5 of impulses is one of a carrier current mo ulated at different frequencies. In Figs. 3 and 4, the distinction between the different t es of impulses is one of duration, the selecting impulses being short, while the operating impulses are long. The arrangements here used will serve to illustrate all of the different ways in which a distinction may be rovided between the different types of impulses.

Mechanisms having a plurality of opera tive functions can be selectively controlled by coding the selecting impulses, with a different code for each of the operative functions, leaving the operating impulses to produce the actual operation of the mechanism after the selecting impulses have prepared the mechanism for the desired function. With such an arrangement the usual five operative functions, release, running, lap, service, and emergency of the brakes of a railway train can be readily obtained. In each of the two cases here disclosed, one selecting impulse prepares the brake controlling mechanism for the emergency function. Two selecting impulses prepare it for the lap function, three dition of the auxiliary brake controlling mechanism. A second selecting impulse prepares a circuit in the caboose for causing a lap condition of the auxiliary control, a third impulse prepares a circuit for the running condition of the brakes, and a fourth impulse prepares a circuit for establishing the release condition of the brake mechanism. To obtain impulse which efiects the brake condition prepared by the selecting im ulses.

In my system, after eac selecting impulse from the locomotive has reached the caboose, the caboose ap aratus sends a selecting impulse back to t e locomotive which repares a circuit toset up an indication. he first selecting impulse received on the locomotive prepares a circuit for the emergency indication; the second selecting impulse repares a circuit for the la indication; the t ird impulse, the running indication; and the fourth, the release indication. After the first operating impulse has been sent from the locomotive to the caboose, and the auxiliary mechanism has assumed the desired condition, the caboose apparatus sends back an o ratingimpulse which energizes the indicating device, showing that the caboose mechanism isgin the desired position. If no operating impulse is sent from the locomotive or from the caboose to the locomotive a service application results at each end of the train. Since the operating impulses do not make any change in the circuits set up by the selecting impulses, it is unnecessary to repeat the code of selecting impulses after the mechanism has once effected the function desired. Both circuits are retained continuously energized by a continuous exchange of operating impulses between the caboose and the locomotive. Provision is' made to put the apparatus on both the locomotive and the cabooseback at their starting position whenever the locomotive driver changes the brake condition by changing the position of the usual engineers brake valve. A new selecting code is then started that corresponds to the new position of the engineers brake valve. Slow acting characteristics are given to portions of the apparatus of both caboose and locomotive so that the brake valves and indicating devices will remain in any position in which they have been for the length of time necessary for a new position to be put into effect by the process just described. The selecting apparatus is made slightly slow acting so that when both selecting and operating impulses are present the operating impulse will take precedence. This last feature prevents the possibility of any stray impulses fromanother nearby equipment changing the condition of the caboose equipment while that on the locomotive is still sending the operating impulses to retain the caboose mechanism in the position in which it was.

Referring to Fig. 1, the engineers brake valve EV is of the standard type capable of assuming the several brake controlling positions release, running, lap, service, and emergency. As shown schematically on the drawing the contactors 20, 21, 22, and 23 are operatively connected to the handle 2 1 of the brake valve EV, and they are adapted to engage the arcuate members 25, 26, 27 and another.

28, respectively in all positions of the brake valve. Each of the contactors 21, 22 and 23 makecontact with the segments in the columns E, L, R and C which represent emergency, lap, running, and release positions of the valve EV respectively. These se ents are arranged in rows 67, 68, 69, 70, 71, 2 and 17 and Will be identified by their row and column. The contactor 20 enga es with a series of segments 73 whenever t e valve is being moved from one operating position to It will be noted that in the S or service position of the brake valveEV, no segments are provided to engage with any of the contactors.

Relay 1 is a starting relay of a chain of counting relays 2 to 5, inclusive, which prepare circuits through their respective contacts 63, 64, 65 and 66 leading to the indicating' devices 1E, 1L, IR and 10, respectively. The indicating device IE is the emerency indication, IL is the lap indication 1R 1s the running indication, and 1C the release indication as will be more fully described later in. the specifications. These indicating devices are each made slow releasin in order that they will retain the energized position in response to periodical impulses of current.

The locomotive is provided with a generator G adapted to supply modulated carrier current at two different modulating frequencies. One modulating frequency is used for the selecting impulses and the other modulating frequency is used for the operating -impulses. The carrier frequency of the generator G may be, for example, five thousand cycles per second, the modulating frequency for the selecting impulses may be, say, fifty cycles per minute, while the modulating frequency for the operating impulses may be sevent cycles per minute. This generator G is 0 any of 'th'e'types of generators of modulated carrier current, many of which are well known to the art, among them being the vacuum tube type. As this generator forms no part of my invention it is only indicated in the drawing by a symbol, it bein deemed sufiicient to say that energy of the requency of the selecting impulse, leaves the generator by wires 29 and 30, and that the energy of the frequency for the operating. impulses leaves the generator by the wires 29 and 31. It will be understood, of course, that my invention is not limited to the above mentioned frequencies, but that these frequencies are given by way of illustration only.

The locomotive is also provided with an input filter and amplifier A, whose output is fed through the wires 32 and 33 to a selector AS. This amplifier and selector may be of any of the types that are commonly used, which are selectively responsive to modulated carrier current. As this amplifier and selector also form no part of my invention,

they are only indicated in the drawing by a symbol. Energy'of the selecting frequency leaves the selector AS through wires 34 and 35 energizing the relay 36 through a full wave rectifier 37, the circuit being controlled by a back contact 38 of a relay 39. Energy of the operating frequency leaves the selector AS through wires 35 and 40 energizing relay 39 through the rectifier 41.

Inductor coils 42 and 43 are mounted on the locomotive and positioned in an inductive relation with the trafiic rails 11 and 11 respectively. The coil 44 is mounted in an inductive relation with the train coupler 45. These three coils 42, 43 and 44 are connected in series with one outside terminal connected to the wires 46 and 29 leading to the amplifier A and the generator G respectively, while the other outside terminal is connected by a wire 48 to the common return wire 47. There is also provided on the locomotive a sourceof current'shown in the drawing as the battery 81.

Slow releasing relay 74 is energized in series with any one of the indicating devlces 1E, 1L, IR and 1C aswill be evident b an inspection of Fig. 1. When the relay 4 15 energized, current is supplied through its contact 75 to a magnet 76 of an electropneumatic valve SV. With the magnet 76 ener-. gized the valve is held closed, whlle when magnet 76 is deenergized, the valve SV biased to an open condition, connects the brake pipe BP to the atmosphere through a vent of such characteristics as toproduce a service rate of reduction of the brake pilpe pressure and a service application of t e train brakes. It follows-then that as long as any one of the indicating devices is energized, the relay 74 is up and valve SV is closed, and that a failure to energize any one of the indicating devices results in a service application of the brakes.

A sendin relay 51 on the locomotive is provided with an energizing winding and an auxiliary winding and is also made slow releasing. Its energizing winding is provided with three energizing circuits the first of which extends from positive battery through the winding of the relay 51, wire 77, front contact 78 of the relay 1, front contact 79 of the relay 2, when both'relays 1 and 2 are closed in a manner to be described later, wire 80, back contact 132 of relay 39 and the common return wire 47 to the negative terminal of the battery 81. The second circuit for the energizing winding of the relay 51 branches from the wire 77 along wire'82, front contact 83 of the relay 39, wire 84, one of the contacts 63, 64, or 66, the corresponding indicating device, relay 74, wire 180, common return wire 47 and to the negative terminal of the battery 81. The third circuit includes the key 92 connected to wire 47. As will shortly appear, the sending relay 51 is energized over the first of these circuits when impulse is received on the locois ener 'zed b. the second circuit a selecting motive an upon the receipt 0 an operating im ulse on the locomotive. The auxiliary win ing for the relay 51 is controlled by the normally closed key 198, as will appear later in the specifications, to create the signal impulses.

Referring to Fig. 2, the equipment in the caboose is substantially similar to that on the locomotive. The inductor coils 85, 86 and 87 are preferably du licates of the inductor coils 42, 43 and 44 0 Fig.1 and are located in a similar manner. The amplifier A and selector AS in the caboose supply current of the selecting modulating frequency to energize the relay 88 through the rectifier 89,

and current at the operating modulatin frequency to energize the relay 90 throug the rectifier 91. The generator G in the caboose is similar to that on the locomotive and is adapted to supply carrier current modulated at the selecting frequency over the wire 118 and carrier current modulated at the operating frequency over the Wire 179.

6 is the starting relay of a chain of counting relays 7 to 10, inclusive, similar to the counting relays of Fig. 1.

The caboose is provided with a main reservoir M, a feed valve F", and a plurality of ele'ctropneumatic valves D adapted to reproduce the functions of the engineers brake valve on the locomotive. It will be understood, of course, that the caboose is further provided with a compressor, etc., to insure a proper supply of air pressure in the reservoir M Valves DC, DR and DE are each biased to a closed position and each valve is opened when its associated magnet 12 is energized. Valve DS is biased to an open position and is closed when its magnet 12 is energized. When the valve DC is open, that is, when its magnet is energized, main reservoir M is connected with the brake pipe BP-so that the mechanism will then reproduce the condition which exists on the locomotive when the engineers valve is in the release position. \Vhen the valve DR is opened, the brake pipe is connected to the feed valve F thereby reproducing the condition existing on the locomotive when the engineers valve is in the running position. When the valve DS is open, that is, when its magnet 12 is deenergized, the brake pipe is connected to the atmosphere through a vent of such characteristics as to produce a reduction in the brake pipe pressure at substantially the service rate of the usual brake valve to effect the service application of the train brakes. When the valve DE is'opened by its magnet 12 being energized, the brake pipe BP is connected to the atmosphere through a vent of such characteristics as to cause an emergency rate of reduction of the brake pipe pressure and an emergencyapplication of the brakes. When the valve DS is energized and the rep and the function reproduce b the auxiliary the inductor co mechanism corresponds to the ap positionof This selecting maining valves deenergized both the su p1 and the exhaust of the brake ipe are blan ie the brake valve on the locomotive. Tlfema net 12 of each of the several valves is ma e slow releasin so that the corres ondin valve is continuously retained in t e 051- tion corresponding to the energized position when the magnet is intermittently energized. These magnets are controlled by the chain of counting relays in a manner similarto the control of the indicating devices on the locomotive. Attached to the movable part of each of the valves, as indicated by the dotted lines, is a series of contacts adapted to make on their front contacts when the valve is energized and to make on their back contacts when the valve is deenergized.

The single sending relay 51 on the locomotive is replaced in the caboose by two slow releasing sending relays 13 and 14. Relay 13 is used for controlling the selecting impulses sent out by the generator G in the caboose and the relay 14 is used to control the operating impulses, and the signal impulses when used. The caboose apparatus is also provided with two relays 15 and 16 which act to throw the chain of counting relays back to their original starting position preparatory to a change in the position of the electropneumatic valves. 100 is a battery in the caboose to supply direct current to the various circuits. 7

In order to illustrate the operation of my system as shown in Figs. 1 and 2 I will assume that it is dcenergized and that it is desired to set the apparatus at the running position. Normally, of course, the release position would be the one first set up, but the running position will be used, as the apparatus of Figs. 1 and 2 is shown in the running position at the moment when an operating impulse is being delivered by the locomotive equipment and received by the caboose equipment. After the engineer has placed the handle 24 of the brake valve at the running position, he momentarily closes the key 92 to pick up the sending relay 51 by the circuit that extends from positive battery through its energizing winding, the key 92 and the common return wire 47 to the negative terminal of the battery 81. As relay 51 picks up, it closes a circuit extending from the generator G along wire 30, back contact 54 of relay 36, front contact 55 of relay 51, wire 56, arcuate member 27, contactor 22, segment 68, wire 58, back contacts 59, 60, 61 and 62 of relays 2, 3, 4 and 5, respectively, wire 80, back contact 132, common return wire 47, wire 48, inductors 42, 43 and 44, and wire 29 to the other terminal of generator G. It follows then that as long as the relay 51 remains up due to current through key 92 or to its slow releasing characteristics. to close the contact 55, carrier current modulated at the selecting frequency is surpplied to the track throug impulse is: picked u from the track by the in uctors 85, 86 and 87 at the caboose and applied to the input circuit of the am lifier A. This input circuit can be traced rom the outside terminal of coil to thecommon return wire 93 of the caboose, back contact 94 of the sendin relay 13, back contact 95 of the sending re ay 14, wire 96, amplifier A and wire 97 to the outside terminal of the inductor 87. This impulse is amplified and directed to the selector 'AS and through AS and rectifier 89 to the relay 88 as previously described to pick up that relay. As relay 88 picks up it closes its two front contacts 98 and 99, and the two wires C1 and C2 are both connected to the positive terminal of the battery 100 through wire 101, back contact 102 of the relay 15 and wire 103. Current will flow from the wire C1 through the back contacts 104, 105 and 106 of relays 9, 8 and 7 respectively, winding of the starting relay 6 and the common return wire 93 to the negative terminal of battery 100. As the starting relay 6 is energized current flows from the wire C2 through the front contact 107 of relay 6, winding of relay 7 and to the negative battery by the common return wire 93. As relay 7 picks up it opens the circuit to the relay 6 at the back contact 106 but relay 6 is supplied now with current from the wire C1 through its own front contact 135. With relays 6 and 7 both up a circuit is completed extending from positive terminal through the winding of the sending relay 13, wire 108, front contact 109 of relay 6, front contact 110 of relay 7 and wires 111 and 93 to the negative terminal of battery 100. With the relay 13 up, the circuit previously described for the amplifier A is opened at the back contact 94. However, the rela y 88 is now up, and this input circuit is retained closed by the front contact 112 so that the selector AS is still energized and relay 88 remains up as long as the incoming selecting impulse lasts.

At the end of the initial selecting impulse relay 88 drops and cuts power off from the wires C1 and C2 so that the relay 6 drops. Relay 7, however, is retained energized by a stick circuit extending from positive battery along Wire 103, back contacts 113, 114, 115 and 116 of relays 15, 10, 9 and 8 respectively, front contact 117, winding of the relay 7 and to negative battery by the wire 93. As relay 6 drops it opens the circuit to the sending relay 13 at the front contact 109. Relay 13, however, will retain its armature raised for a period due to its slow releasing characteristics. While it remains up after relay 6 drops, an output circuit for the selecting modulating frequency of th generator G is completed. This. output circuit extends from the generator G along wire 118, back contact 119 of relay 88, front contact 120 of sending relay 13, wire 121, back contact 122 of relay 6, front contact 110 of relay 7, wires 111 and 93, inductor coils 85, 86 and 87, and to the opposite terminal of the generator G. I

-A selecting impulse is now supplied to the track at the caboose and when this 1mpulse reaches the locomotive it energizes aniplifier A, Fig. 1, by an electromotive force generated in the inductors 42, 43 and 44, and operating through wire 46, amplifier A, wire 49, back contact 50 of relay 51 and wires 47 and 48 back to inductor 42. This causes selector AS to pick up the relay 36, which in turn connects the two wires C3 and C4 to the positive battery terminal. Current flows then from the wire C3 through the back contacts 123, 124 and 125 of relays 4, 3 and 2, res ectively, to the startin relay 1 energizing t at relay. As the starting relay 1 picks up, current flows from the wire C4 through the front contact 126 to the relay 2 energizing that relay. As relay 2 is picked up it opens the circuit to the relay 1 at contact 125 but relay 1 still is supplied with current from the wire C3through its own front contact 127. Relay 2 also closes its stick circuit that extends from the positive battery to the arcuate member 26, contactor 21, segment 67 back contacts 128, 129 and 130 of relays 5, 4 and 3 respectively, front contact 131, winding of relay 2, and to the negative terminal of the battery 81 by the wire 47. With both relays 1 and 2 energized current is supplied to the energizing winding of the sending relay 51 by the circuit previously traced which includes the front contact 7 8 of relay 1 and front contact 79 of relay 2. At theend of the incoming selecting impulse the relay 36 drops to deprive relay 1 of current by disconnecting the wires C3 and C4 from positive energy. Relay 2, however, remains energized by the stick circuit described above. As relay 1 drops and while the sending relay 51 remains up due to its slow releasing characteristics, the output circuit for the selecting modulating carrier current is again completed. This time this output circuit extends along wire 30, back contact 54 of relay 36, front contact 55 of relay 51, wire 56, arcuate member 27, contactor 22, segment 71*, wire 134, back contact 133 of relay 1, front contact 79 of relay 2, wire 80, back contact 132, wires 47 and 48, inductor coils 42, 43 and 44, and wire 29 to the generator G. This outgoing selecting impulse will continue during the slow release period of the sending relay 51.

When this second selecting impulse reaches the caboose the relay 88 is again energized to again connect positive power to the wires C1 and C2. As the relay 7 is now up, current the common return wire 93 throplgh the front contact 146 of the relay 7 and t e front contact 147 of the relay 8 to energize the sending relay 13. At the end of this second selecting. impulse the rela 88 drops to disconnect the wires C1 and 2 from positive power and the relay 7 is deenergized while the rela 8 is retained energized by the stick circuit t at extends along the wire 103 and the back contacts 113, 114 and 115 of the relays 15, 10 and 9, respectively. As'relay 7 drops, the circuit to the sending relay 13 is opened and during the interval that the armature of relay 13 remains up the output circuit for the selecting modulated carrier current is again closed, the circuit being completed this time through the back contact 148 of relay 7 and the front contact 147 of the relay 8 and thus a second selecting impulse is supplied to the track by the caboose apparatus.

When this second selecting impulse from the caboose reaches the locomotive it energizes the input circuit which in turn picks up the relay 36 to again connect the Wires C3 and C4 to positive power. As the relay 2 is now upv current flows from the wire C3 through the back contact 136 of the relay 1., front contact 137 of the relay 2, winding of the relay 3 and to the negative terminalof the battery'Sl by the wire 47. As the relay 3 picks up it opens the stick circuit to the relay 2 at the back contact 130 but relay 2 is supplied now with current from the wire C4 through its own front contact 138. With both relays 2 and 3 energized a connection is completed from the wire 77 leading from the energizing winding of sending relay 51 to the common return wire 47 through the front contact 139 of relay 2 and the front contact 140 of relay 3 to energize relay 51.

At the end of this second incoming selecting impulse the relay 36 of Fig. 1 drops and in turn the relay 2 is deprived of power while the relay 3 is retained energized by the stick circuit that includes the back contacts 128 and 129 of relays 5 and 4 respectively and its own front contact 130. After the relay 2 drops, the sending relay 51 remains u during its slow release period and during this period locomotive apparatus on being picked up at stick circuit to the re the caboose energizes the relay 88 again, to supply wires C1 and C2with positive energy. As relay 8 is'now up, current this time is supplied to the relay 9 from the wire C2 through the back contact 149 of relay 7, front contact 150 of the relay 8 and to the coil of relay 9. As the rela 9 picks up it opens the Ya 8 at the back contact 115, but relay 8 is now held energized bycurrent from the wire C1 through its own front contact 151. With both relays 8 and 9 energized, the energizing circuit for the relay 13 is completed through the front contact 152 of relay 8 and the front contact 153 of relay 9. At the end of this third selectin impulse the relay 88 drops and the wires 1 and C2 are again deprived of power with the result that the relay 8 drops while the relay 9 is retained energized by the stick circuit that includes the back contacts 113 and 114. As the relay 8 drops, the circuit to the sending .relay 13 is opened at the front contact 152. During the release period of the sending relay 13 the output circuit for the selecting frequency is again closed through the front contact 120, wire 121, back contact 154 of relay 8, and front contact 153 of the relay 9.

When this third selecting impulse supplied by the caboose apparatus to the track reaches the locomotive the relay 36 is energized again to supply positive power to the wires 03 and C4. As the relay 3 is now up, current flows from the wire C4 to the relay 4 through the back contact 155 of relay 2 and the front contact 156 of the relay 3. As the relay 4 picks up it opens the stick circuit of the relay 3 at the back contact 129 but relay 3 is retained energized by current from the wire C3 through its own front contact 157. With relays 3 and 4 up the sending relay 51 is energized through the front contact 158 of relay 3 and front contact 159 of the relay 4. At the end of this third selective impulse the relay 36 drops to disconnect wires C3 and C4 from positive battery and in turn to deenergize the relay 3 while the relay 4 remains energized by the stick circuit that includes the back contact 128 of relay 5. Durin the release period of the sending relay 51, t e operating output circuit for the generator G is closed this time. This output circuit can be traced from the generator G, along the wire 31, back contact 1640f relay 36, front contact 163 of sending relay 51, wire 162, arcuate member 28, contactor 23, segment 72, wire 161, back contact 160 of relay 3, front contact 159 of relay 4, wire 80,

back contact 132, wires 47 and 48, coils 42,

43 and 44, and to the opposite terminal of the generator G by the wire 29.

contact 166 of re When this operatin impulse of modulated carrier current is pic ed up atthe caboose the relay 90 is energized. With the relay 90 up a circuit is completed from the positive batter terminal through energizing windmg 0 the sending relay 14, wire 165, front ay 90, magnet 12 of the valve DS, wire 167, magnet 12 of the valve DR, front contact 168 of relay 9, and Wires 169, 111 and 93 to the negative terminal of the battery 100. It follows then that the receipt of theoperating impulse in the caboose results in the rela 14 and the magnets of the valves DS and R being energized. As this operating impulse makes no change in the circuit of the counting relays the relay 9 remains energized. At the end of this operatingimpulse the relay 90 drops to open the circuit to the sending relay 14..and the. magnets of the valves DS and DR. During the release period of the relay 14 the output circuit for the operating frequency current on the caboose is closed. This circuit extends from the generator G along the wire 179, front contact 178 of the relay 14, front contact 177 of the valve DS, back contact 176 of the valve DE, front contact 175 of the valve DR, back contact 174 of the valve DC, wire 173, front contact 172 of the relay 9, wire 171, back contact 170 of relay 90, common return wire 93, coils 85, 86 and 87 and wire 97 to the opposite terminal of the generator G. From the foregoing it is to be noted that for the caboose apparatus to supply an operating impulse to the track, the incoming operatlng impulse must have been completed and the proper valves energized to produce the running position of the brakes.

As this operating impulse from the caboose reaches the locomotive and energize the input circuit to the amplifier A,\the relay 39 is energized. When relay 39 is up it completes the energizing circuit for the sending relay 51 through its front contact 83, wire 84, front contact 65 of the relay 4, indicating device, 1R, winding of the relay 74 and wires 180 and 47 to the negative terminal of the battery 81. The energizing of the indicating device 1R indicates that the running condition of the caboose apparatus has been established and the energizing of the relay 74 closes the ma et 76 of the auxiliary service valve SV on t e locomotive.

At the conclusion of this operating impulse the input circuit on the locomotiveis no longer energized and the relay 39 drops. During the slow releasing period of the relay 51 current is supplied over the previously traced output circuit for the operating frequency of the generator G. As this impulse from the locomotive is received at the caboose, the input circuit is energized at the frequency of the o erating current and the relay 90 is selecte The relay 90 then in turn closes the circuit for relay 14 and the ma ets of valves DS and DR and this relay an these magnets are given an energizing an operating impulse to the locomotive. It

follows then that as long as the handle 24 of the 'br-ake'valve EV remains at the running position there is an alternate exchange of operating impulses between the locomotive and the caboose. As the slow release period of the magnets 12 of the valve DS and DR on the caboose, and of the indicating device IR and relay 74 on the locomotive, is made longer than the release period of the sending relay 51 on the locomotive or the sending relay 14 in the caboose, the exchange of the operating impulses will supply alternately an energizing impulse to the service and running valves, and to the indicating device 1R and relay 74 at intervals sufiiciently close together to retain these devices in their energized position.

When the position of the handle 24 of the valve EV is changed the stick circuit for the counting relays 2 to 5, inclusive is open at the contactor 21 and these relays drop back to their original position. At the same time the contactor engages arcuate member and one of the segments 73, completing the circuit for the relay 181' as will be evident by an inspection of the Fig. 1. When relay 181 is once energized it closes its stick circuit through contact 182, wire 183, front contact 184 of the sending relay 51 and to the common return wire 47. That is to say, when relay 181 is once energized it is retained energized until the sending relay 51 drops. To put it in another Way, with the relay 181 once energized it is retained in that condition until the end of the sending of an operating impulse. With the relay 181 up it closes at its contact 185 the operating output circuit of generator G around the now open contacts of the counting relays, and the contactor 23 operated by the valve handle 24. It follows then that with an operating impulse once started it is completed even though the position of the handle 24 may in the meantime be changed. As the relays 2 to 5 are now all down, the selecting output circuit of generator G on the locomotive may also be closed from the common return wire 47 through back contact 132, wire 80, back contacts 62, 61, and 59, wire 58, one of the segments of the 68 row, contactor 22, member 27, wire 56, front contact 55 of the relay 51, back contact 54 and wire 30. \Vhen both a selecting and operating impulse are received at the caboose, energy is supplied to both relays 88 and 90. The selecting relay 88 is made slightly slower acting than the relay 90 so that the operating relay 90 picks up first and opens the circuit for relay 88 at the back contact 186. The caboose apparatus then returns an operating impulse to the locomotive in the usual manner to pick up relay 39. As the counting relays 2 to 5, in-

olusive are now all down, the energizing of the relay 39 completes a circuit for the sending relay 51 that includes the front contact 301 of relay 39 and the back contacts 302, 303, 304 and 305 of. the relays 5, 4, 3 and 2, respectively. The next impulse sent from the locomotive equipment will be of the selecting modulating frequency, since the relay 181 was deenergized after there'lay 51 dropped at the end of the firstjimpulse as the handle 24 was moved. With the starting of a new code of selecting impulses the caboose apparatus and locomotive apparatus will exchange selectin impulses until the counting relays of the caboose equipment corresponds to the new die 24.

Let us next consider the relays 15 and 16 on the caboose. The first operating impulse to pick up the relay closes the circuit to position set up by the valve hanthe relay 16 from positive power through the front contact 187 and the winding of the re-' lay 16to the negative terminal of the battery 100. As relay 16 picks up it closes its stick circuit that includes the back contact 188 of the relay 15 and its own front contact 189.

Relay 16 thenremains energized as long as operating impulses are exchanged alternately between the locomotive and the caboose. The first selecting impulse after a series of operating impulses to reach the caboose as the result of a change in the position of the valve EV, energizes relay 88 to close a circuit from positive power through the front contact 190 and the front contact 191 of relay 16 to the relay 15 energizing that relay. As relay 15 picks up, the circuit for the relay 16 is opened at the back contact 188 with the result that both relays 15 and 16 become deenergized. The picking up of the relay 15 also opens the stick circuit to the counting relays 7 to 10, inclusive and these relays are restored to their original position. -To prevent whichever of the relays 7 to 10 is energized at the time from being reenergized over the stick circuit, the relay 15 is made slightly slow releasing.

In changing from one position of the brakes to another, it may be that whichever of the valves was previously energized is still in the energized osition, due to its slow releasing characteristics, after the new condition has been established. If the valve held through until'the sending relay 14 dropped, no operating impulse could be sent out by the caboose mechanism. In order to prevent this condition a set of contacts-192 to 197, inclusive, are mounted on the valves DC, DR and DE and arranged so that when any two to affect the condition of the caboose circuit since the contact 186 of relay 90 which completes the energizing circuit of the relay 88 is open at such times as relay 90 is energized, and since relay 88 is made slightly slow acting so that whenever an operating impulse from the locomotive arrives with no more delay than is normally the case, relay 90 is picked up before relay 88 even though the frequency required to energize 88 is present. The contact 38 of the relay 39 of Fig. 1 provides the same safeguard for the locomotive equipment as has just been described for the caboose equipment.

The set up of any other operatlng condition of the brakes will be accomplished by the apparatus of Figs. 1 and 2 in a similar manner to that already described in detail for the running position. It will be seen therefore, that under all conditions of the controlling unit 24 on the locomotive, the aux1l1ary brake mechanism in the cabooseestablishes the condition selected and that the caboose equipment supplies a return indication that indicates on the locomotive the condition set up at thecaboose.

A key 198 on the locomotive when depressed, open circuits the special auxiliary coil built into the relay 51. This coil is built with such electrical characteristics that the slowrelease period of the relay 51 is considerably shortened when the coil is open circuited. When an operating impulse arrives at the caboose picking up t e relay 90, a circuit is completed from positive powerthrough the front contact 199, back contact 200 of relay 14 and the winding of relay 201. The relay 14 picks up as usual, but since relay 201 is made quicker acting than relay 14, the relay 201 always picks up on each operating impulse. As soon as relay 14 is up, relay 201 is deenergized due to the rupture of its circuit at the contact 200. Relay 201 is given a slow release period longer than that of the sending relay 51 on the locomotive when the keyl98 is depressed to open circuit the auxiliary coil and shorter than the release period of relay 51 when the key 198is closed. Thus when key 198 is depressed and the period'of sending relay 51 is shortened, therelay 201 on the caboose is still in the up position when the impulse ends and the relay 90 drops. As relay ,9 0 drops at the end of the shortened impulse which is a signal impulse, a circuit is tive serve in a similar manner.

completed from positive power through the back contact 202, and front contact 203 of relay 201, to the signaling device 204. The signaling device 204 is made slow releasing so that it continues to display its signal as long as the key 198 of the locomotiveis depressed. Key 205 on the caboose together with relay 52 and signal 53 on the locomo- It follows then that by these two keys, signaling can take place between the crew in the caboose and the crew on the locomotive.

The form of my invention as disclosed in Figs. 3 and 4 differs from that of Figs. 1 and 2 in two respects. Instead of using two separate modulating frequencies, one for selecting the proper circuits, and another for operating the brake valves, a short impulse is used to select the proper circuits and a long impulse of the same frequency to energize the valves. The second difference to be found in Figs. 3 and 4 is that the slow acting valves and indicating devices used in Figs. 1 and 2 are replaced by fast acting valves and indicating devices and the energy that controls them is controlled by slow acting relays.

As stated earlier in the description the selecting code assumed for the apparatus of the Figs. 3 and 4 is the same as that considered for the Figs. 1 and 2, namely, one selecting impulse for emergency, two selecting impulses for lap, three impulses for running, and four for the release condition, while no code produces a service application of the brakes. After the proper number of selecting short impulses have been exchanged between the locomotive and the caboose, a long impulse is sent out by the locomotive and the brake valves on the caboose energized. A long impulse is then returned to the locomotive to energize the proper indicating device and also the auxiliary service valve on the locomotive which is biased to an open position. After this procedure, long impulses are alternately exchanged between the two locations as long as the same brake valve condition remains in effect.

In Fig. 3 the inductors 42. 43 and 44, are similar to those disclosed in the Fig. 1. G1 is a generator of carrier current providing energy for the output circuit and 206 is the sendlng relay controlling the output impulses. This relay 206 is provided with slow release characteristics and has an energizing winding and an auxiliary winding. The auxiliary winding is so built into the relay that when it is short circuited the release period of the relay is materially lengthened. Under operating conditions where the auxiliary winding is open circuited the relay has a release period equal to the duration required for a short'impulse. Under operating conditions where the auxiliary winding is short circuited, the release period is lengthened to the duration required for a long impulse. A1

is an amplifier which is energized by the incoming impulse. Relays 20 208 and 209 choose between the short and long impulses energizing the relay 210 when a short impulse arrives an the relay 211 when a long impulse is received. as will shortly be described. The starting relay 1 and the counting relays 2.to 5, inclusive, are identically the same as those disclosed in Fig. 1 and are controlled by the relay 210 and the position of the handle 24 of the engineers valve in substantiall .the same manner as the counting relays 0 Fig. 1 are controlled by the relay 36 and the handle 24. These counting relays prepare circuits to the indicating devices 2E, 2L, 2R and 2C, and the service valve SV. Slow releasing relay 212 is provided to retain the indicating devices and the relay 74 energized in response to the operating impulses. When the counting relays correspond to the position of the handle 24, the contactor 19 completes a circuit for short circuiting the auxiliary winding coil of'relay 206, making it slower to release than is otherwise the case, thus providing for the sending of along impulse instead of a short impulse.

In Fig. 4 the inductor coils are identical to those of the Fig. 2 and G1 and A1 are preferably identical to the generatorand amplifier respectively of Fig. 3. The relays 213, 214 and 215 function in exactly the same manner as the relays 207, 208 and 209 of Fig. 3 to energize relay 216 in response. to short impulse and the relay 217 in response to a long impulse. The starting relay 6 and the chain of counting relays 7 to 10, inclusive, are identical to those of Fig. 2. Likewise 15 and 16 have the same function as they did in the Fig. 2. 218 and 219 are sending relays to control the output impulses at the caboose. Relay 218 has a released period equal to the duration of a short impulse, while the release period of 219 is equal to the duration required for a long impulse. 220 is a slow release relay to control the energy supplied to the brake valves.

In Fig. 4 the caboose is provided with the same set of electropneumatic valves as described for Fig. 2, however, the actual valves themselves are not shown on the figure in order to simplify the drawing. It is deemed sufiicient to sa that DC is the release valve. DR the running valve, DE the emergency valve and DS the service valve, and that the moving parts of the valves operate circultcontrolling contacts as indicated by dotted lines in the Fig. 4. The valves of Fig. 4 are, however, without any slow releasing characteristics themselves. In Fig. 4, the relay 3L takes the place of the resistance 2L of Fig. 2 in the lap position.

In describing the operation of the apparatus of Figs. 3 and 4 I shall first describe the operation of the impulse selecting relays. Referring to Fig. 4 and assuming all relays to be deener "zed, the receiving circuit extends from t e inductors to the common re-' turn wire 221, back contact 222 of the relay 219, back contact 223 of relay 218, wire 224, amplifier A1 and wire 298 to the o posite terminal of the inductor coils. A l iyass ath from wire 221 to wire 224 is provided y the front contact 225 of relay 216 or by the front contact 226 of the relay 217. Thus this receiving circuit is closed whenever the sending relays 218 and 219 are down or when either the relay 216 or 217 is up. Now let us suppose that a short impulse is received at the caboose. This impulse will pass through the circuit just traced energizing the amplifier A1. The output of the amplifier A1 now supplies energy to the relay 215 by the circuit that extends from one terminal of A1, through wires 299, 221 and 230, winding of relay 215, back contact 227 of the relay 214, back contact 228 of the relay 213'and wire 229 to the opposite terminal of the output circuit of A1. Once the relay 215 is picked up it continues to be energized as long as the incoming impulse lasts by the path through its own front contact 234. As relay 215 is energized current is supplied from positive battery through the front contact 231 and back contact 232 of the relay 214 to the relay 213 to energize that relay. The picking up of relay 213 supplies current to the relay 214 through the front contact 233. Once 214 is energized it then receives current through the front contact 235 of relay 215 and its own front contact 236. It follows then that relay 214 will remain up as long as relay 215 is energized. Also when relay 214 picks up it breaks the circuit to relay 213 at back contact 232. If relay 213 is still up when 215 drops at the end of the incoming impulse, then current is supplied through the front contact 237 of relay 213and the back contact 238 of the relay 215 to the relay 216. In the event relay 213 drops before relay 215 then current is supplied through the back contact 239 of relay 213, front contact 240 of relay 214, and

front contact 241 of relay 215 to the relay 217 to energize that relay. Now the relay 213 has slow releasing characteristics that give it a release period longer than the period of the short impulse and less than the period of the long impulse. It follows'then that the relay 216 will be energized in response to the receipt ofa short impulse and that the relay the relay 210 on the locomotive is energized in response to the receipt of a short impulse at the locomotive and the relay 211 is energized in response to a long impulse.

In order to describe the operation of-the equipment disclosed. in Figs. 3 and 4, I will assume that all apparatus is deenergized and that it is desired to put it in the running condition, that is, the position in which the apparatus is shown in the figures. The eng1neman first places the handle of the valve EV at service position so that the contactor 243 engages segment 244 and completes a circuit for the relay 211 that extends from positive battery through the member 245, contactor 243, segment 244, winding of the relay 211 and to the negative terminal of the source of power. As relay 211 picks up it closes at its front contact 247 a circuit for the energized winding of the relay 206 to energize that relay. The engineman now shifts his handle 24 to the running position and these two relays 211 and 206 become deenergized and as relay 206 is slow releasing its armature remains up'for a time. Between the time relay 211' drops, and the time when the armatures of 206 drop, the output circuit of the generator G1 is completed through the back contact 259 ofrelay 210, back contact '248 of relay 211, front contact 249 of relay 206, wire 246 and inductors 42, 43 and 44. This impulse is short inasmuch as the circuit to the auxiliary coil of the sending relay 206 is now open at the counting relay as will shortly be pointed out.

When this short impulse reaches the caboose it operates the rela s 213, 214 and 215 in the manner described a ove to energize the relay 216, which in turn connects positive energy to the wires C1 and C2 to actuate the starting relay 6 and the counting relay 7, these relays being energized in the same manner as described in connection with Fig. 2. While both relays 6 and 7 on Fig. 4 are energized a. circuit tothe sending relay 218 is completed at the front contacts 250 and 251 of relays 6 and 7 respectively. At the end of the incoming short impulse relay 216 drops, and the output circuit of the generator G1 in the caboose is closed during the release period of the sending relay 218, the circuit being completed at the front contact 252 of relay 218, back contact 253 of relay 217, and the back contact 254 of the relay 216. Thus this first short impulse received at the caboose leaves the relay 7 of the chain of relays energized and completes the output circuit during the release period of the sending relay 218 which release period is made e ual to that of a short impulse. When the rst short impulse reaches the locomotive, the relays 207, 208 and 209 function as described'above, to

select the relay 210 which turn connects positive energy to the wires C3 and C4 causing, thereby, the relays 1 and 2 to be picked lay 210 drops closing the output circuit of the generator G1 on the locomotive through front contact 249 of relay 206, back contact 248 of relay 211 and back contact 257 of the rela 210. As the second short impulse reac es the caboose the impulse selecting relays again energize relay 216 in the same manner as previously described. As therelay 7 is now up the relay 8 is energized when current is supplied to the wires Cl and C2 and again closes the circuit to the sending relay 218. At the end of the impulse the output circuit of the generator G1 is again closed by the circuit previously described. As the second short impulse is returned by the caboose to the locomotive, the relay 210 again becomes energized and the relays 2 and 3 of the chain of relays are actuated to complete the circuit for the energizing winding of the relay 206 so that a third short impulse is sent out by the locomotive apparatus. The receipt of the third short impulse at the caboose again picks up the relay 216 and the relays 8 and 9 are actuated resulting in a third short impulse being returned to the locomotive.

The receipt of the third short impulse on the locomotive actuates relays 3 and 4 of the chain of relays. When the relays 3 and 4 are up, the circuit for the energizing winding of the relay 206 is closed at the front contacts 258 and 259 of relays 3 and 4, respectively. In addition, a circuit for short circuiting the auxiliary coil of relay 206 also is completed as follows: one terminal of the auxiliary winding of relay 206, wire 260, arcuate member 261, contactor 19, segment 262, wire 263, front contact 264 of relay 4, wire 265, front contact 266 of relay 206 and to the opposite terminal of the auxiliarycoil. At the end of the incoming impulse, the output circuit is this time retained closed much longer due to the short circuiting of the auxiliary coil of the relay 206, which is so built around the core of the relay as to materially lengthen the release period. It follows then that the next outgoing impulse to the caboose is a long impulse and that the relay 217 is selected by the impulse selecting relays in response to this long impulse. While the relay 217 is picked up a circuit is closed from pos tive power through the front contact 267 wire 269, front contact 268 of relay 9, magnet 12 of the valve DR, wire 270, magnet 12 of the Valve DS and to the negative terminal of the battery by the common return wire 221. A second circuit is also closed while relay 217 is up, from positive power through the front icked up, the circuit to the energizcontact 271 to the sendin relay 219 energizing that relay. Also t e slow releasin relay 220 is energized bwlhe circuit close at the front contact 272. en the relay 217 drops at the end of the incoming lon impulse the sending -rela 219 holds close during its release erio the output circuit on the caboose. his output circuit extends from one terminal of the generator G1 through the back contact 254 o relay 216, back contact 253 of the relay 217, front contact 273 of the relay 219, front contact 274 of the valve DS, back contact 275 of the valve DE, front contact 276 -of the valve DR, back contact 277 of the valve DC, back contact 278 of the relay 8, front contact 279 of the relay 9, wire 221, the inductor coils and wire 298 to the opposite terminal of generator G1. The characteristics of the release feature of the sending relay 219 are such that the outgoing impulse is a long impulse. As the relay 217 drops at the end of the incomin impulse, the valves DR and DS are retaine ener ized through the circuit now closed at the front contact 280 of the slow releasing relay 220. This last circuit extends from the contact 280 through the back contact 281 of the valve DE, backcontact 282 of the relay 3L, front contact 283 of the valve DR, bac

contact 284 of the valve DC, magnet 12 of the valve DR, wire 270, magnet 12 of the valve DS, and to the common return wire 221. To sum up, therefore, the receipt of along impulse sets the auxiliary brake controlling mechanism in the running condition, and so prepares the output circuit that a long impulse is returned to the locomotive, and also energizes the slow releasing relay 220 in order to retain the valves in their energized condition until thereceipt of the next long impulse. Since there is some delay between the time the im ulse arrives and the time the relay 217 pic s up to energize relay 220, the relay 220 is only energized during a fraction of the time that the impulse is being received. In order to make it ossible to shorten the slow action period 0 relay 220 a circuit is completed at such time as relay 219 is up, from positive battery through the front contact 285 of 219, and the front contact 286 of 220, energizing relay 220, therefore, until the end of the outgoing impulse.

The receipt of the first long impulse on the locomotive results in relay 211 being selected. As relay 211 picks up, the circuit to the slow releasing relay 212 is completed at the front contact 287 energizing that relay. With relay 212 energized, then the circuit to relay 74 and the indicating device 2B is completed at the front contact 288 inasmuch as the front contact 289 of the relay 4 is now also closed. While relay 211 is up, current is supplied to the energizing winding of the relay 206 through the front contact 247, and with the relay 206 once up to close the front contact 266, the auxiliary winding of the relay 206 is short circuited by the circuit pre- I viously traced. The recei t of a lon impulse on the locomotive, there ore, resul s in the energizing of the indicating device 2R and the rela 74 that holds closed the service valve S and also prepares the output circuit to send a long impulse.

From this point on there will be an alter-- nate exchange of long impulses between the locomotive and caboose equipment as long as the handle 24.is retained in the running position; On the caboose the slow releasing relay 220 retains the valves continuously energized in their runnin condition and on the locomotive a similar s ow releasing relay 212 retains theindicatin device 2R continuously energized to indicate that the auxiliary brake controlling mechanism is re roducing the condition set up by the valve V.

In order to illustrate what happens when the position of the valve EV of Fig. 3 is changed, I shall assume that it is shifted from the running to the lap position. When the contactor 243 is between the se ments of the row 290, the stick circuit for t e relay 4 is ruptured and the chain of relays is returned to its original condition. Also as the handle 24 is being moved the contactor 291 enga es a segment of the row 292. If when this appens, relays 210 and 211 are down and relay 206 up, indicating that an impulse is being sent out, the relay 293 is picked up by a clrcuit from positivebattery through the back contact 294 of relay 210, back contact 295 of relay 211, front contact 296 of relay 206, arcuate member 297, contactor 291, one of the row of segments 292, winding of the relay 293 and to the negative terminal of the battery. Once the relay 293 is up it is held energized by a stick circuit until the relay 206 drops at the end of the outgoing impulse. With relay 293 up, the circuit for the auxiliary winding ofthe relay 206 is closed around the contactor 19 and the front contact 264 of the relay 4 by the front contact 398. It follows then that a full length impulse will be sent out even if the position of the handle 24 has been changed. This is done in order to avoid the possibility of sending an impulse of a length between that of a long impulse and a short impulse to which the caboose apparatus would not respond. As the relay 206 drops to end the outgoing impulse it also opens the stick circuit to the relay 293 which is now deenergized and is not reenergized again until the position of the handle 24 is again changed. As the. caboose apparatus next returns a long impulse to select the relay 211, it closes the energizing winding of the relay 206 as usual, but, the auxiliary winding of 206 is not short circuited as the chain of relays 2, 3, 4 and 5 are now all deenergized and as relay 293 is also deenergized. The next outgoing impulse from the locomotive will thus be short impulse to start the lap code corresponding to the new position of the handle 24. In the event a long impulse was bein received at the moment the handle is move from the running position to the lap )OSltion, the counting relays would be set ack pulse after a series of long impulses causes the relays 15 and 16 to function in the same manner as described in connection with Fig. 2 causing the chain of relays 6 to 10 to assume their orlg'inal position and the caboose apparatus to send out a short impulse.

The selecting of any other position of the brake controlling mechanism on the caboose so that it corresponds to the position set up by the valve EV will be accomplished in a slmilar manner to that described for the running position.

While in both Figs. 2 and 4 the service valve DS is the one shown energized in series with any one of the remaining valves in order to carry out the closed circuit principle, it will'be understood that I do not limit myself to this arrangement, and that any one of the valves could be used in series with the remaining valves. Likewise in Figs. 1 and 3, the valve controlled by the relay 74 which is energized when any one of the indicating devices is energized, is spoken of as being adapted to produce a service rate of reduction of the brake pipe pressure. It will be understood that this valve could be just as readily arranged to produce any other of the several operating functions of the brakes if it was so desired.

It is obvious that the same operating impulses that are used to energize the valves in connection with Figs. 3 and 4 may be also used for signaling by being made of a somewhat different length in a manner similar to that disclosed in connection with Figs. 1 and 2.

The control system such as here disclosed in which each impulse is initiated at the end of the received impulse from the other control point, permits a rapid change from one operating function to another since the selecting impulses which accomplish the selecting of the proper circuit may be short and exchanged very rapidly. Also since the entire exchange of selecting impulses which precede a change in the operating function is completed before the operating function is ini tiated at either station, the operating function may be brought about at the two dif- -is first originated at either station an ferent stations at very nearly the same instant. The use of an operating impulse which may be much longer than. the selecting'impulse permits a much slower operation of the relays which carry out the operating function thereby reducing the'wear to which such relays are subject. In control systems for the control of the brakes of a railway train, it has been proposed to arbitrarily divide time into separate intervals, one for transmitting a control impulse and a second for receiving the im ulse. A certain amount of time elapses etween the instant when an im ulse the instant at which it becomes effective at the other station. Any arbitrary time divider has to be so built that the time interval permitted for transmission of a control impulse in either direction is sufiicient under the most unfavorable circumstances. Myinvention is especially adapted to such a control system due to the fact that the end of a received impulse initiates the next transmitted impulse at that station and thus the change from transmission to reception can take place as rapidly as the conditions prevailing at the time permit. A control system such as here disclosed is also highly selective and free from outside interference.

Although I have herein shown and described only certain forms of my invention, it is understood that various changes-and modifications may be made therein within the scope of the appended claims without departin from the spirit and scope of my invention.

i-laving thus described my invention, what I claim is: 4

1. A control system including, a control station, a remote station, an operating mechanism at the remote station having a plurality of operating conditions, means including a source of current adapted to supply a selecting current impulse and an operating current impulse with said impulses having distinctive characteristics, coding means to produce a dilferent code group of selecting impulses for each operating condition of said operating mechanism, a transmitting means at said control station to transmit any one of the different code groups of selecting impulses and an operating impulse, a receiving means at the remote station selectively responsive to the difierent code groups of selecting impulses and to said operating impulse for causing the operating mechanism to establish any desired operating condition, and means to continue to transmit and to receive operating impulses only to retain the operating mechanism in the'condition established.

2. A control system including a control station, a remote station, a mechanism at each station having a plurality of different operating conditions; means at each station to produce a different code of selecting current impulses for each of the different operating conditions of said mechanisms, and to produce an operating current impulse having a' characteristic distinctive from that of the selecting current impulse; manual operated means at the control station to determine the code of selecting impulses, and atransmitting and a receiving means at each station adapted to first exchange selecting current impulses of the code determined by the manual means and then to exchange operating impulses for causing the mechanism at each station to register the operating condition corresponding to the code determined by the manual means. p

3. A control system including, a control station, a remote station,.a mechanism at each station having a plurality of operatlng conditions, a circuit associated with each mechanism for each of its operating conditions, means at each station adapted to supply a different code of current impulses for each of the different operating conditions of said mechanisms, a manual operated means at the control station to select the code, a transmitting and a receiving means at each station arranged to exchange current impulses between said stations until the code selected is completed, and means responsive to such exchange of current impulses to prepare the circuit of each mechanism corresponding to the code selected by the manual means.

4. A control system comprising, a mechanism having a plurality of operating condltions, a circuit for each of the plurality of" operating conditions, a transmitting means including a source of current adapted to supply a different code group of selecting current impulses for each of said operating condltions and to supply intermittently an operating current impulse with characteristics different from the selecting impulses, a manual o era ted means to select the code group of selecting impulses, receiving means influenced by the selecting and operating impulses of the transmitting means, and controlling means selectively controlled by said receiving means to prepare the circuit for the operating condition corresponding to the code selected in response to the code group of selecting impulses and to energize the circuit prepared in response to the intermittent suppl of operating impulses.

5. Xpparatus for the control of train brakes comprising, a brake controlling mechanism adapted to produce the release, running and brake applying conditions of the train brakes, a circuit for each of said conditions associated with said brake controlling mechanism, means including a source of current to supply selecting current impulses and operating current impulses having distinctive characteristics, manually controlled means to code the selecting impulses with a different code for each of said conditions, and a recelving means selectively responsive codes for difi'erent positions of said engineers valve, auxiliary brake oont'rolling mechanism at another point on the train capable of reproducing the functions of the engineers valve, a circuit for each function associated with said auxiliary mechanism; and a controlling means associated with said auxiliary mechanism, selectively responsive to the several codes of said selecting impulses to prepare thecircuit corresponding to the respective function and to energize the circuit prepared in response to an operating impulse for causing the function of the auxiliary mechanism to register with the position of the engineers valve.

7. Apparatus for the control of train brakes comprising in combination with the usual engineers brake valve on the locomotive, a source of current impulses, means for coding the current impulses at different codes for different positions of the engineers valve, an auxiliary brake controlling mechanism located at another point on the train capable of reproducing the functions of the engineers valve, a source of current impulses at said other point on the train, means for coding the current impulses of the second mentioned source at a difl'erent code for the different functions of the auxiliary mechanism, an indicating mechanism on the locomotive capable of indicating the different positions of the auxiliary mechanism, controlling means partly on the locomotive and partly at theother location arranged to exchange current impulses between the two locations until a code is completed, and means rendered active by said controlhng means in response to such exchange of current impulses for causing the auxiliary mechanism to register with the position of the engineers valve and the indicating mechanism to indicate the position of the auxiliary mechanism.

8. A control system including, means located at one point for supplying a code group of current impulses, means located at another point for supplying a similar code group of current impulses, controlling means located partly at each of said locations arranged to alternately exchange current impulses between said locations until the code group is completed, a signaling circuit at each location, means ateach location governed by said controlling means to energize said signaling circuits in response to the complete exchange pulse, controlling means located partly at each of said locations arranged to alternately exchange selecting impulses between said locations until the code group is completed and then to exchange operating impulses, a signaling circuit at each location, means at each location governed by said controlling means to prepare the signaling circuits in response to the exchange of the code group of selecting impulses and to energize said signaling circuits in response to the exchange of the operating impulses.

10. A control system including, means located at one point for supplying a code group of selecting current impulses and a single operating impulse, means located at another point for supplying a similar code group of current impulses and a single operating impulse, controlling means' located partly at each of said locations arranged to alternately exchange selecting impulses between said locations until the code group is completed and then to exchangeoperating impulses, a controlling circuit at each location, means ateach location governed by said controlling means to prepare the controlling circuits in response to the exchange of the code group of selecting impulses and to energize said circuits in response to the exchange of the operating impulses, and an operating mechanism at each location rendered active by the energizing of the associated controlled circuit.

11. A control system including, means located at one point for supplying first a code group of selecting current impulses and then operating impulses, means located at another point for supplying first a similar code group of selective current impulses and then operating impulses, controlling means located partly at each of said locations arranged to alternately exchange selecting impulsesbetween the said' locations until the code group is completed and then to alternately exchange operating impulses, a controlling circuitat each location, means at each location governed by said controllingmeans to prepare the controlling circuits in response to the exchange of the code group of selecting impulses and to supply said circuits with an energizing impulse of current in response to the exchange of each operating impulse.

12. A control system including, means 10- cated at one point for supplying short current impulses and long current impulses, manually controlled means for arranging the short impulses into a plurality of difierent codes'with each code consisting of a different number of impulses, ineans located at a second point for supplying similar short and long current impulses and to arrange said short impulses into similar code groups, controllmg means located partly at each of the two points arranged to alternately exchange short impulses 'etween the two points until the code selected by the manual means is completed and then to alternately exchange long current impulses, a circuit corresponding to each code for each of the two points,

means at each point governed by the controlling means to prepare the circuit corresponding to the code exchanged and to supply the means to vary the rate of exchanging impulses of current, and means responslve to the new rate of impulses to energize both the operating mechanisms and the signalling devices.

14'. A control system including, a control station, a remote station, an operating mechanism at each of said stations, means at each station to supply impulses of current, a transmitting and receiving means partly at each station arranged to exchange separate impulses of current with each of a given duration between the two stations to-intermittent- 1y energize the operating mechanism, a signaling device at each station, manually controlled means for changing the duration of each impulse of current, and means responsive to the impulses of the second mentioned duration to energize both the operating mechanism and the signaling devices.

15. A control system including, a control station, a remote station, an operating mechanism at each of said stations, a sending and receiving means partlyat each ofsaid stations arranged to alternately transmit a control current in each direction between the stations for causing an active condition of each of the operating mechanisms, and manually controlled means for causing said control currents to also transmit signaling messages between the two stations without interfering with the active condition of either of said operating mechanisms.

16. A control system including, a control station, a remote station, an operating mech-. anism at each of said stations, a sending and receiving means partly at each of said stations arranged to transmit a control current in each direction between the stations for causin an active condition of each of the operat ng mechanisms, and manually c0ntrolled means for causing said control currents to transmit a message in either direction between the stations or to transmit messages simultaneously in both directions between the stations without interfering with the active condition of either of said operating mechanisms.

17. A control system including, means for supplying different codes of selecting current impulses of modulated carrien current of a given modulating frequency, other means for supplying operating current impulses of modulated carrier current having a difierent modulating frequency, a receiving means selectively responsive to the difii'erent codes of selecting current impulses and also selectively responsive to the different modulating frequencies of said carrier current, and an operating mechanism having a plurality of operating conditions selectively controlled by said receiving'means.

, 18. A control system including, means for supplying any one group of a plurality of different code groups of selecting impulses of modulated carrier current of a given modulating frequency and then periodically supplying operating impulses of modulated carrier current having a different modulating frequency, a receiving means selectively re sponsive to the different modulating frequencies of the carrier current, and an operating mechanism controlled by the receiving means having a plurality of operating conditions moved to a different condition in response toa code group of selecting impulses of each of the different codes and retained active in that condition in response to the periodic operating impulses.

19. A control system including, a control station, a remote station, an operating mechanism at the remote station having a plurality of operating conditions, means including a source of carrier current adapted to supply a selecting current impulse and an operating current impulse each having a distinc tive modulating frequency, coding means to establish a different code group of selecting impulses for each operating condition of said operating mechanism, a transmitting means at said control station to transmitany one of the different code groups of selecting impulses and an operating impulse, a receiving means at the remote station selectively responsive to the different code groups of selecting impulses and selectively responsive to the modulating frequencies of the selecting receiving periods arranged to render the associated transmitting means active during the transmitting period and to render the receiving means. active during the receiving period, and said controlling means capable of initiating the next transmitting period at its location immediately following the termination of a received impulse and to initiate the next receiving period immediately following the termination .of a transmitted I impulse and thereby permit current impulses to be exchanged between the two locations without any delay between the impulses.

21. A control system including, two spaced locations, transmitting and receiving means at each location capable of either transmitting or receiving current impulses, a quick acting relay and a slow release relay at each location arranged to be energized in response to a received impulse by the associated transmitting and receiving means and to cause said means to transmit an impulse during the slow release period of the slow release relay when said relays are deenergized, and means controlled by the relays of a location to initiate the sending of the next impulse from that location immediately upon the completion of the received impulse and thereby permit current impulses to be exchanged between the two locations without any delay between the impulses.

22. A control system including, two spaced locations, a controlling means at each loca-.

tion to divide time into transmitting and receiving periods, means at each location governed by the controlling means to automatically exchange impulses of current between the two locations during said transmitting and receiving periods, a mechanism at each location each retained in an operating condition by the alternate exchange of current impulses, and means at each location to cause the controlling means at the same location to immediately initiate a transmitting period at the end of a received impulse.

23. A control system, including, two spaced locations, a controlling means at each location to divide time into transmitting and receiving periods, means at each location governed by the controlling means to automatically exchange impulses of current between the two locations during said transmitting and receiving periods, a mechanism at each dition by the alternate exchangeof current impulses, and means at each location to prevent the controlling means at the same location to initiate the transmittin of an impulse as long as an impulse is bemg received.

In testimony whereof I aflix my signature.

' LEE DEVOL. 

